Apparatus for boring radial holes in a coaxial cable

ABSTRACT

Certain types of couplers utilized in tapping a coaxial cable intermediate along its length require boring a plurality of radial holes in the coaxial cable to closely regulated predetermined depths and without shorting the inner and outer conductors. Tool apparatus for boring such holes is provided and consists of a tool block having a cable-receiving channel disposed across one of its surfaces and a clamp member for securing a coaxial cable in the channel. A plurality of threaded apertures extend from the bottom of the channel through the tool block to the opposite surface. A hollow tubular tool holder is threaded along a portion of its length and provided with a stop shoulder adjacent the thread termination such that it may be introduced into the threaded apertures and screwed down until the shoulder abuts the tool block surface. A hollow cylindrical tool provided with peripheral teeth at one end is secured within the tool holder in a predetermined position such that, when the tool holder is screwed home, a circular cut of the desired depth is directed radially in the coaxial cable. Where a cut through the inner conductor is required, the surface of the tool block against which the tool holder shoulder abuts is undercut to the desired extent to permit the necessary deeper cut. Subsequently, a second nonthreaded tool holder, used in conjunction with a modified drill bit, is introduced into the tool block apertures after the circular cut has been made and twisted to remove the core.

UnitedStates Patent [72] Inventor William A. Rheinielder Phoenix, Ariz.

[211 App]. No. 15,162

[22] Filed Feb. 27, 1970 [45] Patented Dec. 7, 1971 [73] AssigneeRJCommunicatlon Products, Inc.

[54] APPARATUS FOR BORING RADIAL HOLES IN A COAXIAL CABLE 3 Claims, 8Drawing Figs.

[52] US. Cl 408/97, 408/l0l. 408/l02 [5 l] Int. Cl. B23h 49/02 [50]Field 0! Search 408/97, 101, 102

[56] References Cited UNITED STATES PATENTS 1,638,230 8/l927 Alsaker-408/102 X Primary Examiner-Francis S. Husar Attorney-Drumrnond, Cahill &Phillips ABSTRACT: Certain types of couplers utilized in tapping acoaxial cable intermediate along its length require boring a pluralityof radial holes in the coaxial cable to closely regulated predetermineddepths and without shorting the inner and outer conductors. Toolapparatus for boring such holes is provided and consists of a tool blockhaving a cable-receiving channel disposed across one of its surfaces anda clamp member for securing a coaxial cable in the channel. A pluralityof threaded apertures extend from the bottom of the channel through thetool block to the opposite surface. A hollow tubular tool holder isthreaded along a portion of its length and provided with a stop shoulderadjacent the thread termination such that it may be introduced into thethreaded apertures and screwed down until the shoulder abuts the toolblock surface. A hollow cylindrical tool provided with peripheral teethat one end is secured within the tool holder in a predetermined positionsuch that, when the tool holder is screwed home, a circular cut of thedesired depth is directed radially in the coaxial cable. Where a cutthrough the inner conductor is required, the surface of the tool blockagainst which the tool holder shoulder abuts is undercut to the desiredextent to permit the necessary deeper cut. Subsequently, a secondnonthreaded tool holder, used in conjunction with a modified drill bit,is introduced into the tool block apertures after the circular cut hasbeen made and twisted to remove the Core.

PATENTEUDEI: nan

SHEET 1 BF 3 INVENTOR.

WILLIAM A. RHEINFELDER ATTORNEYS PATENTED DEC 7 I971 SHEET 2 BF 3INVENTOR. W|LL|AM, A RHEINFELDER BY ATTORNEYS PATENTEUHEB mn- 3525623sum 3 or 3 'IIIII/IIII IF/III Bikini INVENTOR.

WILLIAM A. RHEINFELDER BY gz mx away/wo- ATTORNEYS APPARATUS FOR BORINGRADIAL HOLES IN A COAXIAL CABLE This invention relates to cutting toolsand, more particularly, to tool apparatus for boring closely controlledradial holes in coaxial cable.

The necessity for providing convenient connectors for coupling to acoaxial television cable has become more acute with the advent of cabletelevision (CATV). Typically, a CATV system will utilize extensiveantenna and receiving equipment for receiving and amplifying atelevision signal. The receiving equipment is connected to a main trunkwhich may also be provided with suitable repeaters to maintain signalstrength along the cable. The main trunk link will usually service anumber of feeder lines, and the latter will ordinarily be installed in aneighborhood and be positioned along the telephone poles or perhapsunderground in the case of underground utility service. The feeder linesare typically coaxial cables having a single solid inner conductor ofcopper and a single solid tubular aluminum outer conductor withdielectric material between the two to maintain positioning. A plasticsheath will normally surround the cable.

The feeder lines are tapped at convenient locations to provide theappropriate television signal to individual dwellings through smallercoaxial cables called house drops. A house drop cable is usually formedof a single solid inner copper wire surrounded by a semiflexible plasticmaterial which supports a braided copper outer conductor. The entirecable is covered with an insulating and weatherproofing sheath. The tapon the feeder line is normally installed by semiskilled personnelunacquainted with the complexities of high-frequency signal transmissionand the problems that can be caused by improperly or poorly installedtaps; further, the environment in which the tap or coupler existsdictates that the coupler be weatherproofed and be completely imperviousto moisture and other elements.

A coaxial cable coupler which has been found especially useful fortapping such feeder lines is disclosed in my copending applications,Ser. No. 801,700, filed Feb. 24, I969, entitled Method and Apparatus forCoupling to a Coaxial Cable and Ser. No. 834,323, filed June 18, 1969,entitled Connector for Attachment to a Coaxial Cable. While theconnector disclosed therein functions with highly desirablecharacteristics, the use of the referenced connector requires the priorboring of a plurality of radial holes in the coaxial cable to be tapped,and these holes must be carefully controlled as to depth whilecompletely avoiding the shorting of the inner and outer conductors sincethe tapping operation typically occurs while the coaxial cable iscarrying a signal. In a preferred embodiment, the coupler requiresdrilling three closely spaced radial holes in the coaxial cable with thecenter hole severing the inner conductor and both outer holes piercingonly the outer conductor.

It is a broad object of this invention to provide tool ap paratus forboring closely controlled radial holes in a coaxial cable.

It is a more specific object of this invention to provide tool apparatusfor boring a plurality of radial holes in a coaxial cable atpredetermined mutual positions along the length of the cable and topredetermined depths.

These objects are achieved, according to a presently preferredembodiment of the invention, by providing a tool block having a cablereceiving channel across one of its surfaces and a clamp member forsecuring a coaxial cable therein. Three spaced-apart threaded aperturesextend from the bottom of the channel through the tool block to theopposite surface. The threaded apertures accommodate a tubular toolholder which is threaded along a portion of its length and which isprovided with a shoulder adjacent the thread termination which abuts thetool block surface to limit precisely the depth to which the coaxialcable is penetrated. The boring operation is carried out by a hollowcylindrical tool secured within the tool holder in a predeterminedposition. The hollow cylindrical tool is provided, at its working end,with longitudinally directed saw teeth arranged in a circular pattern.The

tool holder is provided, on the unthreaded portion of its outer surface,with a hexagonal shape such that it may be screwed down with a wrenchthereby making a circular cut to a predetermined depth in the coaxialcable. In the pattern contemplated, the center one of the three holesmust be cut deeper than the outer holes in order to sever the innerconductor as well as penetrate the outer conductor. The additionalcutting depth is effected by undercutting the surface of the tool blockaround the center aperture where the tool holder shoulder abuts the toolblock surface. After a circular cut has been made, a core remains whichis removed by using a second, nonthreaded work holder in conjunctionwith a modified drill bit which is introduced into the tool blockapertures and twisted to ream the core out.

The subject matter of the invention is particularly pointed out anddistinctly claimed in the'concluding portion of the specification. Theinvention, however, both as to organization and method of operation, maybest be understood by reference to the following description taken inconnection with the accompanying drawing, of which:

FIG. I is a perspective view of the tool block of the present inventionshowing the tool block clamp in position;

FIG. 2 is a cross-sectional view of the tool block of FIG. 1 taken alongthe lines 2--2;

FIG. 3 is a cross-sectional view of the tool block of FIG. 1 taken alongthe lines 33;

FIG. 4 is a perspective view of the cutting tool of the presentinvention;

FIG. 5 is a perspective cutaway view of the tool holder whichaccommodates the cutting tool of FIG. 4;

FIG. 6 is a plan view of the core removing tool;

FIG. 7 is a perspective cutaway view of the tool holder for the coreremoving tool illustrated in FIG. 6; and

FIG. 8 is a cross-sectional view of the tool block with a coaxial cablein place showing the cutting and reaming tools in position at thetermination of cutting and core removing operations, respectively.

Referring now to FIG. 1, it will be observed that a tool block 1 has achannel 2 which extends across the whole of one of its surfaces. A clampsupport member 3 is secured to the tool block 1 and extends upwardlybeyond the surface in which the channel 2 is formed. The clamp supportmember 3 is provided with a plurality of apertures 4 for receiving acorresponding plurality of projections for guiding and securing a clampmember 5 in position. The clamp member 5 is provided with a channel 6which, when the clamp member 5 is in position on the tool block I,complements the channel 2 in the tool block I to provide a passageway ofsubstantially circular cross section. A threaded stud 7 projectsupwardly from the tool block 1 through a hole in the clamp member 5 andreceives a nut 8 which functions to tighten the clamp member 5 inposition.

FIG. 2 is a cross section of the tool block I taken along the lines 2-2of FIG. I and FIG. 3 is a cross section of the tool block 1 taken alongthe lines 3-3 of FIG. 1. The manner in which the clamp support member 3is secured to the tool block 1 is best shown in FIG. 2 where it will beobserved that a first bolt 9 and a second bolt (not shown) from thecutaway portion fixes the clamp support member 3 rigidly to the toolblock 1. First, second and third threaded tool guide apertures 10, I1,and I2, extend through the body of the tool block I from the bottom ofthe channel 2 to the opposite surface 13 of the tool block I. The firstand third tool guide apertures 10 and I2 terminate flush with thesurface 13. However, the second tool guide aperture 11 is provided withan undercut I4 which creates a shoulder depressed below the surface 13.The reason for the undercut I4 will become apparent as the descriptionproceeds. The passageway comprising the complementary channels 6 and 2has an approximately circular cross section as may be seen in FIG. 2.The dimensions of the channels 2 and 6 are such that a coaxial cable tobe tapped is held snugly within the passageway by tightening the nut 8onto the stud 7.

The threaded tool guide apertures 10, 11, ad 12 receive a tool holder21, shown in FIG. 5, containing a cutting tool 15 illustrated in FIG. 4.Referring to FIG. 4, the cutting tool 15 is a hollow tubular structurewith a passageway 16 extending throughout its length. The working and ofthe tool 15 terminates in a plurality of circumferentially disposedsawteeth l7 brought to a sharp serrated leading edge 18 and extendingrearwardly and outwardly. The area to the rear of the sawteeth 17 ismachined to a smaller diameter to avoid shorting the outer conductor tothe inner conductor in those boring operations in which the centerconductor is secured. A pair of flat areas 19 and 20 disposed 90 apart,are provided at the rearward end of the cutting tool 15 for securing itin place within the tool holder 21 of FIG. 5.

Referring now to FIG. 5, the tool holder 21 generally comprises a hollowtubular structure provided with threads 22 cut into a reduced diameterportion of its length. The forward and rearward sections of the interiorhave, respectively, larger and smaller diameters such that thetransition area between the two diameters effects an internalcircumferential shoulder 23. The rearward external portion 24 of thetool holder 21 is in a hexagonal configuration to facilitate applyingthe necessary torque to perform the cutting operation as will beexplained more fully below. An internally threaded washer 25 provides anexternal shoulder to control the depth to which the tool holder 21 maybe screwed home. A threaded aperture 26 and a second threaded aperture(not shown in FIG. 5) receives set screws which are tightened againstthe flat areas 19 and 20 of the cutting tool 15 of FIG. 4 when thecutting tool 15 is inserted in the tool holder 21 and fitted against theinternal shoulder 23.

FIG. 6 illustrates a second tool 27 generally comprising a drill bitwith a specially configured leading edge 28 directed approximately 1from normal to the longitudinal axis of the tool 27. A pair of flatareas 29 and 30 are provided at the rearward end of the tool 27 forsecuring the tool within its work holder.

The work holder for receiving the tool 27 of FIG. 6 is depicted in FIG.7, and generally comprises a hollow tubular structure having a circularexternal configuration along a first portion 31 of its length with theremaining rearward portion 32 having a hexagonal configuration. Anundercut 33 between the portions 31 and 32 provides a positive seat onthe forward face 34 of the portion 32. A first threaded aperture 35 anda second threaded aperture (not shown) disposed 90 from the aperture 35are adapted to receive set screws for securing the tool 27 of FlG. 6 inposition after it has been seated against the internal shoulder 36within the bore of the tool holder 37.

The manner of using the tool apparatus is best understood with referenceto FIG. 8 which depicts the first tool holder 21 with the tool 15 inplace screwed home in the threaded tool guide aperture 11 and the secondtool holder 37 with the tool 27 in place bottomed in the threaded toolguide aperture 12. It will be understood that the normal use of the toolholders 21 and 37 is sequential rather than simultaneous, the lattershown in FlG. 8 merely for purposes of illustration. A coaxial cable 38is inserted into the passageway comprising the channels 2 and 6 (FIGS. 1and 2) and is fixed in place by tightening the clamp 5. The coaxialcable 38, shown in cross section in FIG. 8, consists of an innerconductor 39, an outer circumferential conductor 40, insulatingdielectric material 41 separating the inner and outer conductors and anouter insulating cover 42. As previously noted, the tool apparatus isused to bore a center radial hole in the coaxial cable which penetratesthe outer conductor and severs the inner conductor 39. This operation isperformed by introducing the tool holder 21 into the center tool guideaperture 11 and screwing it down utilizing a suitable wrench on thehexagonally shaped rearward portion 24 of the tool holder. The toolholder 21 is thus screwed down until the washer 25 seats against thebottom of the undercut 14 at which point the penetration issubstantially as shown in FIG. 8 where it will be observed that thesawteeth 17 of the cutting tool 15 have severed the inner conductor 39leaving a core extending into the passageway 16 of the tool 15.

As previously noted, the center tool guide aperture 11 is flanked byouter tool guide apertures 10 and 12 which are not provided with anundercut corresponding to the undercut 14. Thus, when the tool holder 21is introduced into the tool guide apertures 10 and 12, the surface 13 ofthe tool block 1 provides a stop limiting the depth of penetration shortof the inner conductor 39 of the coaxial cable 38. In FIG. 8, thecoaxial cable adjacent the tool guide aperture 12 has been bored inaccordance with the requirement for the outer holes whereas the coaxialcable adjacent the tool guide aperture 10 has not yet been tapped.

In the normal sequence of operations, all three positions are firstbored using the tool holder 21 in conjunction with the cutting tool 15leaving three cores of material to be removed. The cores are removed byintroducing the tool 27, in its tool holder 37, successively into thetool guide apertures 10, II and 12 and twisting in a clockwisedirection, utilizing a wrench on the hexagonal surface 32, if necessary,to ream out the core material thereby providing a cleanly defined hole.The specially configured leading edge 28 of the tool 27 insures asubstantially fiat bottom to the radial holes cut into the coaxial cable38 for proper accommodation of the coupler subsequently attached afterremoval of the coaxial cable 38 from the tool block 1.

While the principles of the invention have now been made clear in anillustrative embodiment, there will be immediately obvious to thoseskilled in the art many modifications of structure, arrangement,proportions, the elements, materials, and components, used in thepractice of the invention which are particularly adapted for specificenvironments and operating requirements without departing from thoseprinciples.

lelaim:

1. Apparatus for boring and clearing holes to a predetermined depth in acoaxial cable, comprising:

a. a tool block, said tool block being provided with a first channelextending across the full length of a first one of its surfaces, saidfirst channel configured to substantially conform to a portion of theouter surface of a coaxial cable, a clamp member adapted for use withsaid tool block, said clamp member having a second channel disposed inparallel with and superimposed over said first channel, means fortightening said clamp member against said tool block, said first andsecond channels cooperating to form a passageway substantiallyconforming to the outer surface of a coaxial cable such that a second ofcoaxial cable disposed in said passageway is securely held when saidclamp member is tightened against said block, a tool guide apertureextending through said tool block, said tool guide aperture disposedperpendicular to said first channel and said first surface, said toolguide aperture being threaded along at least a portion of its length;

b. a tool holder, said tool holder comprising a coaxially bored tubularstructure having a threaded portion along its outer surface for threadedengagement with said tool guide aperture, the coaxial bore through saidtool holder including first and second portions with corresponding firstand second diameters, said first diameter being larger than said seconddiameter, a step transition between said first diameter and said seconddiameter providing an internal shoulder, circumferential externalshoulder means on the periphery of said tool holder adjacent theterminus of said threaded portion for limiting the distance throughwhich said tool holder may be threaded into said tool guide aperture;and

c. a tubular cutting tool adapted to be inserted into and fixed in saidtool holder, a first end of said cutting tool configured in a pluralityof longitudinally directed sawteeth arranged in a circular pattern, asecond end of said cutting tool dimensioned to seat against saidinternal shoulder in said first tool holder to define the relativelongitudinal relationship between said tool holder and said cuttingtool.

2. Apparatus for boring and clearing holes to a predetermined depth in acoaxial cable, comprising:

a. a tool block, said tool block being provided with a first channelextending across the full length of a first one of its surfaces, saidfirst channel configured to substantially conform to a portion of theouter surface of a coaxial cable, a clamp member adapted for use withsaid tool block, said clamp member having a second channel disposed inparallel with and superimposed over said first channel, means fortightening said clamp member against said tool block, said first andsecond channels cooperating to form a passageway substantiallyconforming to the outer surface of a coaxial cable such that a second ofcoaxial cable disposed in said passageway is securely held when saidclamp member is tightened against said block, a plurality of tool guideapertures extending through said tool block, each of said tool guideapertures disposed perpendicular to said first channel and said firstsurface, each of said tool guide apertures intercepting said firstchannel symmetrically, each of said tool guide apertures being threadedalong at least a portion of its length;

b. a first tool holder, said first tool holder comprising a coaxiallybored tubular structure having a threaded portion along its outersurface for threaded engagement with any one of said plurality of saidtool guide apertures, the coaxial bore through said first toolholderincluding first and second portions with corresponding first and seconddiameters, said first diameter being larger than said second diameter, astep transition between said first diameter and said second diameterproviding an internal shoulder, circumferential external shoulder meanson the periphery of said first tool holder adjacent the terminus of saidthreaded portion for limiting the distance through which said first toolholder may be threaded into one of said plurality of said tool guideapertures; and

c. a tubular cutting tool adapted to be inserted into and fixed in saidfirst tool holder, a first end of said cutting tool configured in aplurality of longitudinally directed sawteeth arranged in a circularpattern, a second end of said cutting tool dimensioned to seat againstsaid internal shoulder in said first tool holder to define the relativelongitudinal relationship between said first tool holder and saidcutting tool.

3. The apparatus of claim 2, which further includes:

a. a second tool holder, said second tool holder comprising a coaxiallybored tubular structure, the coaxial bore through said second toolholder including first and second portions with corresponding third andfourth diameters, said third diameter being larger than said fourthdiameter, a step transition between said third diameter and said fourthdiameter providing an internal shoulder within said second tool holder,second external shoulder means on the periphery of said second toolholder for limiting the distance through which said second tool holdermay be threaded into one of said plurality of said tool guide apertures;and I b. a reaming tool adapted to be inserted into and fixed in saidsecond tool holder, said reaming tool dimensioned to seat against saidinternal shoulder within said second tool holder to define the relativelongitudinal relationship between said second tool holder and saidreaming tool.

1. Apparatus for boring and clearing holes to a predetermined depth in acoaxial cable, comprising: a. a tool block, said tool block beingprovided with a first channel extending across the full length of afirst one of its surfaces, said first channel configured tosubstantially conform to a portion of the outer surface of a coaxialcable, a clamp member adapted for use with said tool block, said clampmember having a second channel disposed in parallel with andsuperimposed over said first channel, means for tightening said clampmember against said tool block, said first and second channelscooperating to form a passageway substantially conforming to the outersurface of a coaxial cable such that a second of coaxial cable disposedin said passageway is securely held when said clamp member is tightenedagainst said block, a tool guide aperture extending through said toolblock, said tool guide aperture disposed perpendicular to said firstchannel and said first surface, said tool guide aperture being threadedalong at least a portion of its length; b. a tool holder, said toolholder comprising a coaxially bored tubular structure having a threadedportion along its outer surface for threaded engagement with said toolguide aperture, the coaxial bore through said tool holder includingfirst and second portions with corresponding first and second diameters,said first diameter being larger than said second diameter, a steptransition between said first diameter and said second diameterproviding an internal shoulder, circumferential external shoulder meanson the periphery of said tool holder adjacent the terminus of saidthreaded portion for limiting the distance through which said toolholder may be threaded into said tool guide aperture; and c. a tubularcutting tool adapted to be inserted into and fixed in said tool holder,a first end of said cutting tool configured in a plurality oflongitudinally directed sawteeth arranged in a circular pattern, asecond end of said cutting tool dimensioned to seat against saidinternal shoulder in said first tool holder to define the relativelongitudinal relationship between said tool holder and said cuttingtool.
 2. Apparatus for boring and clearing holes to a predetermineddepth in a coaxial cable, comprising: a. a tool block, said tool blockbeing provided with a first channel extending across the full length ofa first one of its surfaces, said first channel configured tosubstantially conform to a portion of the outer surface of a coaxialcable, a clamp member adapted for use with said tool block, said clampmember having a second channel disposed in parallel with andsuperimposed over said first channel, means for tightening said clampmember against said tool block, said first and second channelscooperating to form a passageway substantially conforming to the outersurface of a coaxial cable such that a second of coaxial cable disposedin said passageway is securely held when said clamp member is tightenedagainst said block, a plurality of tool guide apertures extendingthrough said tool block, each of said tool guide apertures disposedperpendicular to said first channel and said first surface, each of saidtool guide apertures intercepting said first channel symmetrically, eachof said tool guide apertures being threaded along at least a portion ofits length; b. a first tool holDer, said first tool holder comprising acoaxially bored tubular structure having a threaded portion along itsouter surface for threaded engagement with any one of said plurality ofsaid tool guide apertures, the coaxial bore through said first toolholder including first and second portions with corresponding first andsecond diameters, said first diameter being larger than said seconddiameter, a step transition between said first diameter and said seconddiameter providing an internal shoulder, circumferential externalshoulder means on the periphery of said first tool holder adjacent theterminus of said threaded portion for limiting the distance throughwhich said first tool holder may be threaded into one of said pluralityof said tool guide apertures; and c. a tubular cutting tool adapted tobe inserted into and fixed in said first tool holder, a first end ofsaid cutting tool configured in a plurality of longitudinally directedsawteeth arranged in a circular pattern, a second end of said cuttingtool dimensioned to seat against said internal shoulder in said firsttool holder to define the relative longitudinal relationship betweensaid first tool holder and said cutting tool.
 3. The apparatus of claim2, which further includes: a. a second tool holder, said second toolholder comprising a coaxially bored tubular structure, the coaxial borethrough said second tool holder including first and second portions withcorresponding third and fourth diameters, said third diameter beinglarger than said fourth diameter, a step transition between said thirddiameter and said fourth diameter providing an internal shoulder withinsaid second tool holder, second external shoulder means on the peripheryof said second tool holder for limiting the distance through which saidsecond tool holder may be threaded into one of said plurality of saidtool guide apertures; and b. a reaming tool adapted to be inserted intoand fixed in said second tool holder, said reaming tool dimensioned toseat against said internal shoulder within said second tool holder todefine the relative longitudinal relationship between said second toolholder and said reaming tool.